trigonal contract
1Silicon nitride — Preferred IUPAC name Silicon nitride …
2renal system — ▪ anatomy Introduction in humans (human body), organ system that includes the kidneys, where urine is produced, and the ureters, bladder, and urethra for the passage, storage, and voiding of urine. In many respects the human excretory, or… …
3Metalloid —   13 14 15 16 17   2  B Boron …
